There is no technology currently available for the combined conversion of saturated, unsaturated and chlorinated hydrocarbons as is provided by this invention. However, some work has been done on individual schemes such as oxidation of saturated and unsaturated hydrocarbons alone on precious metal based catalyst, i.e., palladium or platinum. It is also the practice in some ethylene glycol industries to convert hydrocarbons in the carbon dioxide off-gas to CO.sub.2 and H.sub.2 O followed by carbon dioxide vent to the atmosphere or further purification of a small stream of good grade CO.sub.2 by adsorption on carbon. Relevant patents and published applications are discussed below.
German Patent No. DE 4305386 of H. Meye, et al. describes catalyst development in the oxidative purification of saturated hydrocarbon from CO.sub.2 with platinum or palladium based catalyst supported on alpha-Al.sub.2 O.sub.3 with a specific surface area less than 50m.sup.2 /g. The content of platinum is specified to be under 0.2 wt %. The technology described in this patent was developed for food grade purification of CO.sub.2 and is different from the present invention because DE 4305386 deals only with development of a catalyst for the removal of organic impurities, especially saturated hydrocarbons from a CO.sub.2 stream. The present invention enables the removal of chlorinated and unsaturated hydrocarbons through a combination of oxidation, condensation, adsorption and deoxidation steps to obtain CO.sub.2 of high purity.
Japan Patent No. 60086015 of H. J. Ishikawajima describes a method to purify CO.sub.2 by physical separation. Since there is no chemical reaction involved in this patent, it is completely different than the present invention.
The present invention is also distinguished from the prior art in that along with oxidation of unsaturated hydrocarbons on a platinum based catalyst, the invention also deals with the catalytic conversion of chlorinated hydrocarbons to HCl, the adsorption of the HCl and the oxidation of MEG to CO.sub.2 and H.sub.2 O to produce not only carbon dioxide of high purity, but also water which meets the specification of Boiler Feed Water (BFW).